[Gvsig_english] calculating centre points of polygon and ascribing coordinates

Simon Cropper (Botanicus Australia Pty Ltd) scropper at botanicusaustralia.com.au
Tue Nov 24 14:20:45 CET 2009


Hi,

I have found some answers.

First X, Y can be extracted with the field calculator using the 
functions x() and y().

Sextante can be used to extract the centre point of a polygon.

This aside is there any way of consolidating these tasks? Can you 
calculate the centre point of a polygon in gvSIG?

Cheers Simon

Simon Cropper
Botanicus Australia Pty Ltd
PO Box 160, Sunshine, Victoria 3020.
P: 9311 5822. M: 041 830 3437.
mailto: scropper at botanicusaustralia.com.au 
<mailto:scropper at botanicusaustralia.com.au>
web: www.botanicusaustralia.com.au <http://www.botanicusaustralia.com.au>



Simon Cropper (Botanicus Australia Pty Ltd) wrote:
> Hi Everyone,
>
> Can someone tell me if gvSIG can be used to establish the centre point 
> of a polygon?
>
> ... and subsequently place the X and Y coordinates in fields in the 
> attribute table of the polygon shapefile?
>
> ... or alternatively create a point file representing the centrepoint 
> and be able to assign the XY values to that shapefile.
>
> What I regularly do in alternative programs (OpenJUMP, Kosmo, Sextante) 
> is create a point file showing the centrepoint of a set of polygons 
> (usually representing the sites I have surveyed) and then using ArcView 
> assign the XY coordinate of the points to the northing+easting fields. 
> Reproject into Lat-Long and repeat. These coordinates are used to report 
> the sites locations to government agencies.
>
> How would you do this in gvSIG?
>
> Can you use Jpython to do this?
>   


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